To remove material from large areas, it is desirable to have a large pushing structure to allow the structure to clear a wider swath across the surface. A typical application is the removal of snow from a paved area such as a road, runway, or parking lot. Conventional snow plows, having a wide blade for pushing the snow aside, have classically been used.
More recently, wider structures called “pushers” have been employed. In addition to having a wider blade, pushers include side boards which frequently extend forward on either side of the blade to direct the material forward and reduce spillage to the sides. Pushers are typically mounted to a bucket loader vehicle, either attached to the conventional bucket or in place thereof. Due to their large size, pushers may need to be removed from the loader vehicle for transport between work sites. One approach to overcome this deficiency is to make the pusher structure foldable for storage and transport, as taught in U.S. Pat. No. 6,425,196.
A more versatile approach to provide a wider swatch of material removal than is available with a conventional snow plow is to use a “wing plow”. Wing plows have a central main blade with a wing pivotably mounted to each side. The wings can typically be locked in one of three positions. In one position, the wings extend forward and angled outwards from the main blade, providing a wider combined surface for pushing material, while also providing some of the directional effect of a conventional pusher. The wings can also be locked at a position extending forward at 90° to the main blade, where they serve the same function as the side boards of a pusher to provide improved directing of the material. The wings can also be folded in to a position where they are superimposed on the main blade, so as to serve as a narrow plow. The ability to adjust the width of the pushing surface and its directional characteristics makes wing plows especially well suited for applications where material must be removed from both wide open areas and relatively narrow spaces. Additionally, when the wings are folded in, the structure is compact for greater ease of storage or transportation. Like pushers, wing plows are typically mounted to a loader vehicle, either in place of the conventional loader bucket or by being attached thereto.
As noted above, when pushers and wing plows are mounted to a loader vehicle, the pushing structure is either mounted to the bucket or mounted to the loader vehicle in place of the bucket. In either case, the bucket of the loader is unavailable for use when the pushing structure is mounted. There are frequently situations where the material, after being pushed across the surface to a desired location, must then be loaded into a vehicle for transportation. With existing pushers and wing plows, either a second loader vehicle must be employed, or the pushing structure must be inconveniently removed to use the loading vehicle with its bucket. In either case, a large amount of operator time is required to complete the moving and loading operations. This shortcoming has been partially addressed by U.S. Pat. No. 4,723,609, which teaches conversion of a wing plow-like scraper to a bucket loader by providing a bottom pan to be installed by the operator when the wings of the scraper are at right angles. This still requires considerable effort on the part of the operator, and furthermore requires an additional place to store the bottom pan when it is not in use.
An alternative approach has been to flair out the end of a bucket to widen the sweep, as is taught in U.S. Pat. No. 6,574,890. However, this results in a blade having a fixed width, which generates problems which the wing plow was designed to cure. Furthermore, if the device is to be effective in distributing the material when the material is pushed to the side, the depth of the bucket should be relatively shallow, which will limit the capacity for loading material when the device is used as a bucket. The broad opening of such a bucket also limits the control of the dumping of the contents, and may not allow the contents to be dumped into a small target, such as the bed of a dump truck.
To allow pushers and wing plows to move material across surfaces that are uneven, the pushing structure must incorporate some degree of flexibility. U.S. Pat. Nos. 5,148,617 and 6,154,986 teach structures for mounting an articulated plow to a vehicle while allowing a limited degree of floating of the plow to accommodate uneven surfaces. The float structure appears to be designed to allow the main blade to tilt a few degrees forward or backwards by pivoting, so as to accommodate undulation in the paved surface as the plow advances; however, the degree of motion appears to be limited to such slight tilting of the blade.
Thus, there is a need for a pushing structure that provides the benefits of a pusher and/or wing plow as well as providing greater ease and efficiency in loading of material, as well as for a mounting structure which allows such a pushing structure to be employed effectively on uneven surfaces.